proposal
A formal plan or suggestion for others to accept.
A proposal is a plan or suggestion that you formally present to someone, asking them to consider and accept it. When you make a proposal, you're saying “here's my idea” and hoping others will agree it's worth doing.
In school, you might write a proposal for a class project, explaining what you want to research and how you'll do it. A city council member might make a proposal to build a new park, describing where it would go and why the community needs it. Scientists write proposals requesting funding for their research, detailing their experiments and why the work matters.
The word often implies something more official or thought-out than a casual suggestion. If you say “let's get pizza” at lunch, that's just an idea. But if you create a detailed plan showing why your school should offer healthier lunch options, complete with costs and benefits, that's a proposal.
In a special context, a proposal also means asking someone to marry you. This kind of proposal is still an offer and a question, just a very important one about spending your lives together.
When you propose something, you're the one making the proposal. Good proposals are clear, well-reasoned, and show you've thought carefully about what you're suggesting and why it's worth considering.